crdb代码阅读02——system数据库初始化流程

表描述定义

pkg/sql/sqlbase/system.go

UsersTable = TableDescriptor{
	Name:     "users",
	ID:       keys.UsersTableID,
	ParentID: keys.SystemDatabaseID,
	Version:  1,
	Columns: []ColumnDescriptor{
		{Name: "username", ID: 1, Type: colTypeString},
		{Name: "hashedPassword", ID: 2, Type: colTypeBytes, Nullable: true},
	},
	NextColumnID: 3,
	Families: []ColumnFamilyDescriptor{
		{Name: "primary", ID: 0, ColumnNames: []string{"username"}, ColumnIDs: singleID1},
		{Name: "fam_2_hashedPassword", ID: 2, ColumnNames: []string{"hashedPassword"}, ColumnIDs: []ColumnID{2}, DefaultColumnID: 2},
	},
	PrimaryIndex:   pk("username"),
	NextFamilyID:   3,
	NextIndexID:    2,
	Privileges:     NewCustomRootPrivilegeDescriptor(SystemAllowedPrivileges[keys.UsersTableID]),
	FormatVersion:  InterleavedFormatVersion,
	NextMutationID: 1,
}

初始化表描述为内存态KV pairs

pkg/server/node.go
pkg/sql/sqlbase/metadata.go

> server.bootstrapCluster
| > server.GetBootstrapSchema
| | > sqlbase.MakeMetadataSchema
| | | > sqlbase.addSystemDatabaseToSchema
| > sqlbase.MetadataSchema.GetInitialValues

将表定义描述转换成内存的kv形式，便于后面进行插入

初始化第一个range，写入到rocksdb

这里将上一步的所有kv对，直接插入rocksdb中

pkg/storage/store.go

func (s *Store) BootstrapRange(
	initialValues []roachpb.KeyValue, bootstrapVersion roachpb.Version,
) error {
	desc := &roachpb.RangeDescriptor{
		RangeID:       1,
		StartKey:      roachpb.RKeyMin,
		EndKey:        roachpb.RKeyMax,
		NextReplicaID: 2,
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:    1,
				StoreID:   1,
				ReplicaID: 1,
			},
		},
	}
	if err := desc.Validate(); err != nil {
		return err
	}
	batch := s.engine.NewBatch()
	defer batch.Close()
	ms := &enginepb.MVCCStats{}
	now := s.cfg.Clock.Now()
	ctx := context.Background()

	// Bootstrap version information. We don't do this if this is v1.0, which is
	// never going to be true in versions that have this code in production, but
	// can be true in tests.
	if bootstrapVersion != cluster.VersionByKey(cluster.VersionBase) {
		if err := engine.MVCCPutProto(ctx, batch, ms /* ms */, keys.BootstrapVersionKey, hlc.Timestamp{}, nil, &bootstrapVersion); err != nil {
			return err
		}
	}
	// Range descriptor.
	if err := engine.MVCCPutProto(ctx, batch, ms, keys.RangeDescriptorKey(desc.StartKey), now, nil, desc); err != nil {
		return err
	}
	// Replica GC timestamp.
	if err := engine.MVCCPutProto(ctx, batch, nil /* ms */, keys.RangeLastReplicaGCTimestampKey(desc.RangeID), hlc.Timestamp{}, nil, &now); err != nil {
		return err
	}
	// Range addressing for meta2.
	meta2Key := keys.RangeMetaKey(roachpb.RKeyMax)
	if err := engine.MVCCPutProto(ctx, batch, ms, meta2Key.AsRawKey(), now, nil, desc); err != nil {
		return err
	}
	// Range addressing for meta1.
	meta1Key := keys.RangeMetaKey(meta2Key)
	if err := engine.MVCCPutProto(ctx, batch, ms, meta1Key.AsRawKey(), now, nil, desc); err != nil {
		return err
	}

	// Now add all passed-in default entries.
	for _, kv := range initialValues {
		// Initialize the checksums.
		kv.Value.InitChecksum(kv.Key)
		if err := engine.MVCCPut(ctx, batch, ms, kv.Key, now, kv.Value, nil); err != nil {
			return err
		}
	}

	lease := roachpb.BootstrapLease()
	updatedMS, err := writeInitialState(ctx, s.cfg.Settings, batch, *ms, *desc,
		lease, hlc.Timestamp{}, hlc.Timestamp{})
	if err != nil {
		return err
	}
	*ms = updatedMS

	return batch.Commit(true /* sync */)
}

1. 初始化第一个range的desc
2. 插入meta2的key
3. 插入meta1的key
4. 插入系统表描述的kv pair
5. commit